The invention relates generally to the injecting of liquid into a moving supply of water through a conduit and more particularly to the controlled injecting of liquid fertilizer into an irrigation system.
It will be understood that this invention is not limited to use with fertilizers injected into irrigation systems, but may be employed for the controlled injection of any liquid into another liquid flowing under pressure.
Prior art devices for the similar purposes can be found in U.S. Pat. Nos. 1,917,704; 2,120,608; 2,227,646; 2,510,373; 3,690,340; 3,776,274 and 3,807,434.
U.S. Pat. No. 1,917,704 teaches adding liquid under pressure from the supply line to the solution tank forcing the liquid from the solution tank into the supply line. A differential pressure is established to cause the liquids to flow into and out of the solution tank.
U.S. Pat. No. 2,120,608 teaches a liquid piston in a tank to apply a downward force on a solution in the bottom of the tank to inject that solution into the supply line by applying line pressure to the top of the piston which applies a downward force on the liquid piston and solution.
U.S. Pat. No. 2,227,646 teaches dispensing fertilizer into an irrigation system by providing a venturi at the point in the supply water pipe where fertilizer is to be introduced from a supply tank and by connecting a pressure head tank between the water pipe behind the venturi and the surface of the liquid fertilizer and locating a needle valve between the water stream and the fertilizer supply pipe. The pressure head is used to balance the pressure in a varying pressure in the supply water pipe and to prevent supply water backup into the fertilizer supply tank. The venturi draws the liquid fertilizer from the fertilizer supply tank.
U.S. Pat. No. 2,510,373 teaches generally injectors and particularly to metering injectors. Deferential pressure in the system due to siphonic action is used to dispense the liquid fertilizer.
U.S. Pat. No. 3,690,340 teaches flow resistors to vary the pressures in a dispensing system for the proportioning of two or more fluids.
U.S. Pat. No. 3,776,274 teaches suction for drawing a liquid chemical from a container for mixing with a liquid flowing through a pipe.
U.S. Pat. No. 3,807,434 teaches using a venturi to create a differential pressure between a container of chemical and a fluid flow stream to dispense chemical into the stream.
U.S. Pat. No. 4,391,390 teaches the use of fluid flow to create compressed air for dispensing a concentrated solution into the flow line. There is no teaching of any means for infinite variable metering of the concentrate into the fluid flow line, preventing the flow of liquid from the tank generating the pressurized air into the tank of concentrate when the pressure generating tank is filled with the flow liquid or means for automatically draining flow liquid from the container creating the pressurized air when the liquid flow is terminated.
U.S. Pat. No. 4,391,390 teaches a devise for dispensing two or more different chemicals, one of which is under pressure, into a fluid flow line. This system teaches a non-constant mixed fluid flow.
The present invention represents a significant improvement over the prior art by providing an improved liquid fertilizer dispensing device for use in commercial gardening or other purposes.